Photographic material



3,300,312 PHOTOGRAPHIC MATERIAL Jozef Frans Willems, Wilrijk-Antwerp, and Joseph Louis de Munck, Heide-Kalmthout, Belgium, assiguors to Gevaert Photo-Producten N.V., Mortsel-Antwerp, Belgium, a company of Belgium Claims priority, application Belgium, Sept. 26, 1962, 41,992, Patent No. 622,859 No Drawing. Filed Sept. 16, 1963, Ser. No. 309,281 5 Claims. (Cl. 96-85) This invention relates to a photographic material having incorporated therein compounds preventing the formation of small spots caused by the action of heavy metals and/ or compounds of heavy metals upon the light-sensitive layer and at the same time preventing a too high static charging of the photographic material.

Although an utmost care is taken in the manufacture of light-sensitive material, it has not proved practicable to avoid incidental contamination by particles of heavy metals such as iron particles or of compounds of heavy metals such as rust particles of such light-sensitive material. These particles generally originate from the wear and the corrosion of the casting material. Traces of these metals or metal compounds are sometimes present in the photochemicals used and may even be present in the supports such as supports of paper, film and glass upon which the photographic emulsions are coated.

Particles of metal or metallic compounds are harmful particularly in the present environment because they are generally chemically reactive which means that they exert a secondary action upon the light-sensitive emulsion and can enlarge the defects which are caused by their presence directly and which would otherwise be for the most part invisible to the naked eye consequently, depending upon the nature of the particle and the kind of the emulsion applied, light and dark spots become visible after treating the exposed light-sensitive material in the usual photographic baths.

Metallic particles in the photographic layers can 'react rather slowly and the corrosion products formed can diffuse away from the central nucleus. These corrosion products can have a sensitizing or a desensitizing action on the emulsion so that after the normal bath-treatment the photographic material shows black and white spots respectively.

Furthermore, most of these metals or their compounds can act as reducing agents and cause a spontaneous development which leads to black spots. On the contrary other influences, as where the latent image is affected or the development hindered, lead to white spots. In all these cases the resulting spot is always larger than the dust particle which is the underlying cause of this undesirable phenomenon. This conclusion can easily be verified e.-g. by bleaching out with a usual bleaching agent, the silver from the material showing the black spot. Nearly always the black spot disappears but in the centre a very small nucleus remains which can only be seen by enlarging.

Also fine metal particles or dust consisting of metal compounds which are present in a non-light-sensitive adjacent layer have an equally disadvantageous influence on the superimposed or underlying light-sensitive layer. The harmful corrosion products of the metal particles or the dissolved ingredients of the metal com-pounds can readily reach by diffusion the light-sensitive layer to cause the above-mentioned faults.

It has now been found that it is possible to prevent spot formation in a photographic light-sensitive material comprising a support and at least one silver halide emulsion layer by incorporating into said material sulfosalicylic acid and/or at least one water-soluble salt of sulfosalicylic acid.

United States Patent 0 ice These compounds act not only as spot inhibitors but as antistatic agents which means that they prevent an accumulation of electric charges on the photographic material, as a result for instance, of rubbing, and so prevent sparking when winding up and unwinding the photographic material as well as the attraction of dust particles by the photographic material.

Salts of sulfosalicylic acid which are very well suited for use in a material according to the present invention are the monosalts especially the mono-alkali salts and the disalts for instance the di-alkali salts.

The compounds employed according to the invention should be so provided as to be in effective contact with the emulsion layer. Thus they may be incorporated into the support, for instance a paper support and/or into at least one of the water-permeable layers present at the same side of the support as the light-sensitive silver halide emulsion layer, the concentration of said compounds varying according to the compo-und'chosen and the nature of the layer wherein the compound is to be incorporated. Also, these compounds are very often incorporated into the light-sensitive silver halide emulsion layer itself, the concentration of said compound varying fromsome mg. to 10 and more g. per sq. m. of light-sensitive material.

Sulfosalicylic acid and/or soluble salts of sulfosalicylic acid are usually previously dissolved, for instance in water. If the compounds are to be incorporated into the support, said support may be dipped in the above solution. However, when the compounds are to be incorporated into a water-permeable layer or layers the above solution is mostly added to the coating composition of the layer or layers involved. The compounds employed according to the present invention may also be incorporated into a photographic material in combination with known compounds (cf. French patent specifications, Nos. 1,249,593, 1,249,594 and 1,288,867) used for preventing heavy metals, their corrosion products and their compounds from disadvantageously influencing the light-sensitive silver halide emulsion layer. With such a combination still bet ter results in preventing spot formation can be obtained.

The compounds according to the present invention when incorporated into a photographic element show the advantage of not having any influence on the photographic characteristics aimed at such as e.g. contrast, sensitivity, stability and fog. Consequently they can be incorporated into high sensitivity, low sensitivity, high contrast, low contrast emulsions and into acid as well as into alkaline emulsions.

A further advantage is that the compounds of use according to the invention are inert with respect to other emulsion additives such as eg dispersing agents, color couplers, surface active agents, optical bleaching agents, antioxidizing agents, sensitizers, anti-fogging agents, stabilizers, hardening agents and plasticizers.

The compounds according to this invention find versatile applications in any negative and positive material of the black-and-white and color photography such as cinefilm, X-ray film, light-sensitive silver halide emulsion materials used in processes for photomechanical printing and light-sensitive silver halide and non-ligh-t-sensitive transfer materials used for the manufacture of copies by means of the silver halide diffusion transfer process.

The following examples illustrate the present invention.

Example 1 A first photographic material is manufactured as follows: Onto a support of cellulose triacetate a subbing layer is coated from a suspension of gelatin in organic solvents in such a way that 10 g. of solid substance is present per 30 sq. m. of photographic material. Thereupon a second gelatin layer is coated in such a way that 7.5 g. of gelatin is present per 35 sq. m. of photographic material. Finally a silver bromoiodide X-ray emulsion is coated. Onto said silver bromoiodide emulsion layer finely divided corrosion particles of the casting material are scattered whereupon another thin gelatin covering layer is applied.

A second photographic material is manufactured in the same way as the first with the difference, however, that to the coating composition from which the second gelatin layer is coated 80 cc. of a 10% aqueous solution of the mono-sodium salt of sulfosalicylic acid is added per litre.

A third photographic material is manufactured in the same way as the second using, however, a double amount of said 10% solution of the mono-sodium salt of sulfosalicylic acid.

The three materials are developed in a developing bath of the following composition:

Water (40 C.) cc 800 Monomethyl-p-aminophenol sulfate g 4 Sodium sulfite (anhydrous) g 65 Hydroquinone g 10 Sodium carbonate (anhydrous) g 45 Potassium bromide g 5 Water up to cc 1000 The first material shows many black spots, the second material only a few and the third material shows no spots at all.

Example 2 Three light-sensitive materials are manufactured in an analogous way as in Example 1 with the dilference, however, that in the manufacture of the second and third material the aqueous solutions of the sodium salt of sulfosalicylic acid are added to the coating compositions from which the light-sensitive silver halide emulsions are coated. The surface resistivity of said materials are measured at 20 C. and a relative humidity of 50% by means of two electrodes having a length of cm. and placed on the emulsion side of the photographic material at a distance of 1 cm. from each other.

The resistivitiy of the material without sulfosalicylate is more than 10 ohm whereas the resistivity of the materials containing sulfosalicylate is about 10 ohm. As to the black spots equivalent results are obtained as with the materials of Example 1.

We claim:

1. Photographic light-sensitive material comprising a support, at least one light-sensitive silver halide emulsion layer and in effective contact with said emulsion layer a member selected from the group consisting of sulfosalicylic acid and at least one Water-soluble salt of sulfosalicylic acid.

2. Photographic light-sensitive material comprising a support, at least one light-sensitive silver halide emulsion layer and a member selected from the group consisting of sulfosalicylic acid and at least one water-soluble salt of sulfosalicylic acid, said member being present in the light-sensitive silver halide emulsion layer.

3. Photographic light-sensitive material comprising a support, at least one light-sensitive silver halide emulsion layer and a member selected from the group consisting of sulfosalicylic acid and at least one water-soluble salt of sulfosalicylic acid, said member being present in at least one water-permeable layer coated at the same side of the support as the light-sensitive silver halide emulsion layer.

4. Photographic light-sensitive material comprising a support, at least one light-sensitive silver halide emulsion layer and a member selected from the group consisting of sulfosalicylic acid and at least one water-soluble salt of the sulfosalicylic acid, said member being present in the support.

5. Photographic light-sensitive material comprising a support, at least one light-sensitive silver halide emulsion layer and in effective contact with said emulsion layer a No references cited.

NORMAN G. TORCHIN, Primary Examiner.

R. H. SMITH, Assistant Examiner. 

1. PHOTOGRAPHIC LIGHT-SENSITIVE MATERIAL COMPRISING A SUPPORT, AT LEAST ONE LIGHT-SENSITIVE SILVER HALIDE EMULSION LAYER AND IN EFFECTIVE CONTACT WITH SAID EMULSION LAYER A MEMBER SELECTED FROM THE GROUP CONSISTING OF SULFOSALICYLIC ACID AND AT LEAST ONE WATER-SOLUBLE SALT OF SULFOSALICYLIC ACID. 